The interplay between soil physical parameters during the recovery from anoxic stresses （reoxidation） is largely unrecognized. This study was conducted to chaxacterise the soil aeration status and derive correlation...The interplay between soil physical parameters during the recovery from anoxic stresses （reoxidation） is largely unrecognized. This study was conducted to chaxacterise the soil aeration status and derive correlations between variable aeration factors during reoxidation. Surface layers （0-30 cm） of three soil types, Haplic Phaeozem, Mollic Gleysol, and Eutric Cambisol （FAO soil group）, were selected for analysis. The moisture content was determined for a range of pF values （0, 1.5, 2.2, 2.7, and 3.2）, corresponding to the available water for microorganisms and plant roots. The variability of a number of soil aeration parameters, such as water potential （pF）, air-filled porosity （Eg）, oxygen diffusion rate （ODR）, and redox potential （Eh）, were investigated. These parameters were found to be interrelated in most cases. There were significant （P 〈 0.001） negative correlations of pF, Eg, and ODR with Eh. A decrease in water content as a consequence of soil reoxidation was manifested by an increase in the values of aeration factors in the soil environment. These results contributed to understanding of soil redox processes during recovery from flooding and might be useful for development of agricultural techniques aiming at soil reoxidation and soil fertility optimisation.展开更多
Zinc(Zn) deficiency in paddy soils is often a problem for rice production.Flooding can decrease metal availability in some noncalcareous soils through different mechanisms associated with soil redox status.Laboratory ...Zinc(Zn) deficiency in paddy soils is often a problem for rice production.Flooding can decrease metal availability in some noncalcareous soils through different mechanisms associated with soil redox status.Laboratory experiments were performed in order to better understand the processes that governed the dynamics of Zn in non-calcareous paddy soils at varying redox potentials(Eh).Airdried non-calcareous soil samples collected from four different paddy field sites in the Philippines were submerged and incubated in a reaction cell with continuous stirring and nitrogen purging for 4 weeks,and then purged with compressed air for another week to reoxidize the system.The Eh of the four soils started at 120 to 300 mV,decreased to —220 to —300 mV after 100 to 250 h of reduction,and was maintained at this low plateau for about 2 weeks before increasing again upon reoxidation.Zinc solubility showed contrasting patterns in the four soils,with two of the soils showing a decrease in soluble Zn as the Eh became low,probably due to zinc sulfide(ZnS) precipitation.In contrast,the other two soils showed that Zn solubility was maintained during the reduced phase which could be due to the competition with iron(Fe) for precipitation with sulfide.Differences in the relative amounts of S,Fe,and manganese(Mn) oxides in the four soils apparently influenced the pattern of Zn solubility after flooding.展开更多
基金Supported by the Ministry of Science and Higher Education of Poland(No.N 305 009 32/0514)
文摘The interplay between soil physical parameters during the recovery from anoxic stresses （reoxidation） is largely unrecognized. This study was conducted to chaxacterise the soil aeration status and derive correlations between variable aeration factors during reoxidation. Surface layers （0-30 cm） of three soil types, Haplic Phaeozem, Mollic Gleysol, and Eutric Cambisol （FAO soil group）, were selected for analysis. The moisture content was determined for a range of pF values （0, 1.5, 2.2, 2.7, and 3.2）, corresponding to the available water for microorganisms and plant roots. The variability of a number of soil aeration parameters, such as water potential （pF）, air-filled porosity （Eg）, oxygen diffusion rate （ODR）, and redox potential （Eh）, were investigated. These parameters were found to be interrelated in most cases. There were significant （P 〈 0.001） negative correlations of pF, Eg, and ODR with Eh. A decrease in water content as a consequence of soil reoxidation was manifested by an increase in the values of aeration factors in the soil environment. These results contributed to understanding of soil redox processes during recovery from flooding and might be useful for development of agricultural techniques aiming at soil reoxidation and soil fertility optimisation.
基金supported by the Global Rice Science Partnership(GRiSP) Staff Development Fundthe Swiss Agency for Development and Cooperation(SDC) awarded to Dr.S.M.Impa,International Rice Research Institute,Philippines,through its Research Fellow Partnership Programme
文摘Zinc(Zn) deficiency in paddy soils is often a problem for rice production.Flooding can decrease metal availability in some noncalcareous soils through different mechanisms associated with soil redox status.Laboratory experiments were performed in order to better understand the processes that governed the dynamics of Zn in non-calcareous paddy soils at varying redox potentials(Eh).Airdried non-calcareous soil samples collected from four different paddy field sites in the Philippines were submerged and incubated in a reaction cell with continuous stirring and nitrogen purging for 4 weeks,and then purged with compressed air for another week to reoxidize the system.The Eh of the four soils started at 120 to 300 mV,decreased to —220 to —300 mV after 100 to 250 h of reduction,and was maintained at this low plateau for about 2 weeks before increasing again upon reoxidation.Zinc solubility showed contrasting patterns in the four soils,with two of the soils showing a decrease in soluble Zn as the Eh became low,probably due to zinc sulfide(ZnS) precipitation.In contrast,the other two soils showed that Zn solubility was maintained during the reduced phase which could be due to the competition with iron(Fe) for precipitation with sulfide.Differences in the relative amounts of S,Fe,and manganese(Mn) oxides in the four soils apparently influenced the pattern of Zn solubility after flooding.
